\begin{table}[ht] \centering
\newcolumntype{R}{>{\raggedleft\arraybackslash}X}
\newcolumntype{L}{>{\raggedright\arraybackslash}X}
\newcolumntype{C}{>{\centering\arraybackslash}X}

\caption{Test}
\label{tab:abi_denv}
{\scriptsize
\begin{tabularx}{\raggedleft}{@{}lCCCC@{}}

\toprule
&{(1)}&{(2)}&{(3)}&{(4)} \tabularnewline \midrule
{}&{}&{}&{}&{} \tabularnewline
\midrule \addlinespace[\belowrulesep]
Age enrollment 20--25 Months Mean&0.214&0.937&69.122&0.983 \tabularnewline
Age enrollment 9--15 Months Mean&0.234&0.864&93.634&0.964 \tabularnewline
P-value&\textbf\{(0.000)\}&\textbf\{(0.000)\}&\textbf\{(0.000)\}&\textbf\{(0.000)\} \tabularnewline
N&1.7e+04&3.0e+04&3.0e+04&3.0e+04 \tabularnewline
Age enrollment 15--20 Months Mean&0.228&0.904&73.265&0.975 \tabularnewline
Age enrollment 9--15 Months Mean&0.234&0.864&93.634&0.964 \tabularnewline
P-value&\textbf\{(0.038)\}&\textbf\{(0.000)\}&\textbf\{(0.000)\}&\textbf\{(0.000)\} \tabularnewline
N&1.9e+04&3.3e+04&3.3e+04&3.3e+04 \tabularnewline
Age enrollment 20--25 Months Mean&0.214&0.937&69.122&0.983 \tabularnewline
Age enrollment 15--20 Months Mean&0.228&0.904&73.265&0.975 \tabularnewline
P-value&\textbf\{(0.000)\}&\textbf\{(0.000)\}&\textbf\{(0.010)\}&\textbf\{(0.000)\} \tabularnewline
N&1.6e+04&2.9e+04&2.9e+04&2.9e+04 \tabularnewline
\bottomrule \addlinespace[\belowrulesep]

\end{tabularx}
\\ \parbox{\raggedleft}{\scriptsize Note:}
}
\end{table}
